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Metamorphic rocks of the 1985 Tibet Geotraverse, Lhasa to Golmud

Harris, N. B. W.; Holland, T. J. B. and Tindle, A. G. (1988). Metamorphic rocks of the 1985 Tibet Geotraverse, Lhasa to Golmud. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 327(1594) pp. 203–213.

URL: http://www.jstor.org/stable/38188
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Abstract

Two examples of uplifted basement have been studied in the Lhasa Terrane of the Tibetan Plateau. The Nyainqentanglha orthogneisses are bounded by staurolite--garnet schists to the north which record prograde metamorphism at 5.0 ± 1.3 kbar, 610 ± 70 degrees C Garnet--sillimanite xenoliths within the orthogneiss suggest that peak temperatures reached at least 700 ± 70 degrees C at 5.1 ± 2.5 kbar. These P/T fields reflect high T/low P metamorphism during Eocene subduction, and indicate that the syntectonic Nyainqentanglha orthogneiss was emplaced at depths greater than 10 km. Sillimanite-bearing assemblages from the Amdo gneisses in the northern Lhasa Terrane provide evidence of crustal anatexis at temperatures 680 degrees C. This event is poorly constrained in time but is probably Cambrian or earlier. Within the Kunlun Terrane, biotite and garnet isograds north of the Xidatan Fault indicate an increase in metamorphic grade from north to south, reaching peak metamorphism at 470 ± 30 degrees C, 4.3 ± 1.5 kbar synchronous with the emplacement of the Triassic batholith. Regional metamorphism was followed by uplift of at least 2 km before emplacement of post-tectonic, early Jurassic granites.

Item Type: Journal Article
ISSN: 1471-2962
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 13125
Depositing User: Elizabeth Lomas
Date Deposited: 26 Feb 2009 14:58
Last Modified: 02 Dec 2010 20:19
URI: http://oro.open.ac.uk/id/eprint/13125
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